Re: Bears and Butterflies

[boblong@xxxxxxxxxxx (Robert Long)]

On Wed, 27 Nov 1996 13:26:24 +0000 (GMT), Andy Finney wrote:

|Nice to have a discussion on the group that didn't involve chemistry :-)=
 As

In that case, let me re-raise two items of old business that never got
resolved and see what comments (if any) they may elicit from the
current group.

Before this list started, Willem and I had a conversation on the
Usenet about a photography I'd seen a number of years earlier that
purported to show heat loss from a house.  It had been taken at night
and looked pretty unreal, with "ectoplasm" oozing from the doors and
windows.  Willem said it could not have been photographed with regular
IR film, because film is sensitive to near-IR only, and heat is on the
far end of the spectrum.  Maybe he's right; maybe the picture was made
through a night-vision scope.  I just don't remember.  On the other
hand, there are the iron pictures made on IR film that do show the
heat.  And, as discussed here earlier, whether a given wavelength
should be considered as heat depends on what materials we're talking
about.  Anyone have any further thoughts on whether it might be
possible--using a long exposure at night, no doubt--to actually
photograph heat loss on HIE?

More recently I raised a question (and got one specific wrong) on a
peculiarity of certain pigments that I don't understand.  I once had a
lot of old lacquer recording blanks that I had to strip to send the
aluminum substrates off for what today we'd call recycling.  I
discovered that when you looked through a single layer of the lacquer,
it looked sort of a characterless blue color.  But when I doubled the
thickness to two layers it looked deep red (very much like a Wratten
29), and when I increased the number of layers above two, the red got
progressively deeper, but only gradually.  Similarly, there are bulbs
in the New York subway tunnels that play a similar trick.  At a
distance, you see a ruby red glint, but when you get close it turns
out to be a blue bulb.  (That's what I got wrong--I had near and far
conditions reversed.  And I don't know what the bulbs are there for.)
I'd be interested in any explanation of these two phenomena.

Bob Long
(boblong@xxxxxxxxxxx)

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Topic No. 10